The cost, complexity, and power consumption of data centers has been steadily increasing over the years. This has been driven by several factors including the power requirements of fast switching ASIC switch and router chips, the costs of high speed optical interfaces, and the cooling infrastructure required to cool the fast server processers, switches, and routers. For example, the power requirements for networking devices in data centers (e.g., routers) which used to be approximately 5% is projected to approach 40% in a few years. This increase is because the processor chips in the routers have significantly increased in size and complexity and will continue to increase to keep up with the increasing speed requirements.
This massive data transfer including the latency and speed requirements has led to an evolution of the data center architecture from the hierarchical three-tier design including core routers, aggregation or distribution routers, and access switches, to a flat, non-hierarchical, topology where all devices are exactly the same number of segments away. This topology called “leaf-spine” leads to predictable and consistent amount of delay or latency between nodes. Although the leaf-spine data center topology is well-suited to cater for East-West traffic (data designed to travel inside the data center such as to storage elements), oversubscription of links may occur where more traffic is generated than can be aggregated onto an active link at a time. The leaf-spine architecture allows to more easily expand capacity as compared to the traditional hierarchical topology, by deploying additional spine switches and extending the uplinks to every leaf switch. However, this solution to overcoming oversubscription to cope with more East-West traffic leads to increasing cost, complexity, and power consumption in the data center.